Express your answer as a mixed number simplified to lowest terms. $18\dfrac{7}{9}-6\dfrac{4}{12} = {?}$
Explanation: Separate the whole numbers from the fractional parts: $= {18} + {\dfrac{7}{9}} - {6} - {\dfrac{4}{12}}$ Bring the whole numbers together and the fractions together: $= {18} - {6} + {\dfrac{7}{9}} - {\dfrac{4}{12}}$ Subtract the whole numbers: $=12 + {\dfrac{7}{9}} - {\dfrac{4}{12}}$ Simplify each fraction: $= 12 + {\dfrac{7}{9}} - {\dfrac{1}{3}}$ Find a common denominator for the fractions: $= 12+\dfrac{7}{9}-\dfrac{3}{9}$ Subtract the fractions: $= 12+\dfrac{4}{9}$ Combine the whole and fractional parts into a mixed number: $= 12\dfrac{4}{9}$